JPH0583168A - Relay amplifier for high frequency transmission line - Google Patents

Abstract

PURPOSE:To implement the communication of a state signal representing the state of the relay amplifier between the relay amplifier and a center at all times. CONSTITUTION:A 1st branching filter 22 is connected to an outgoing output/ incoming input terminal 20 and a signal is separated to an incoming path 24 and an outgoing path 26 via the 1st branching filter 22, mixed by a 2nd branching device 28 and connects to an outgoing input / incoming output terminal 30. Then amplifiers 27, 33 are inserted respectively in both the paths. Furthermore, a switch 32 implementing on/off control and a band pass filter 37 are inserted to the incoming path in the parallel connection state. The band pass filter 37 acts like interrupting only a prescribed specific frequency band in the transmission frequency band. Then the carrier frequency of a state signal representing the control state of the relay amplifier is set to a prescribed frequency band. Then the state signal is always communicated to a center independently of the switching state of the switch device 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay amplifying device for a high frequency transmission line which is provided in a bidirectional high frequency electric signal transmission line using a coaxial cable and which can block the transmission of signals in the upstream direction.

[0002]

2. Description of the Related Art Conventionally, a coaxial transmission line in CATV is known as a bidirectional high-frequency electric signal transmission line using a coaxial cable. An example of the transmission path in this CATV is shown in FIG. That is, the transmission line 1 connects the center 2 and the plurality of terminal devices 3a and 3b, and the distributor 4 is appropriately arranged in the transmission line 1 to make a branch in a dendritic manner and a large number of relay amplifiers 5a and 5b. By being provided, the amount of attenuation accompanying signal transmission is corrected, and the center 2 is surely moved to each terminal device 3a, 3b side.
I am able to convey information from. By appropriately setting the frequency used during transmission, bidirectional communication is possible on the transmission line 1 of one line.

Here, focusing on the transmission of information in the up direction from the terminal devices 3a, 3b side to the center 2 side, the electrical signals actually transmitted from the terminal devices 3a, 3b to the center 2 side and , A large number of relay amplifiers 5a, 5b
The noise generated by is transmitted in an interference state. Therefore, it is necessary to secure an appropriate signal voltage level difference between the electric signal and the noise.

Therefore, in a conventional large-scale coaxial transmission line, there is a relay amplifier 5a, 5b which has a built-in reverse switch capable of interrupting upstream information transmission. That is, the relay amplifiers 5a and 5 with the reverse switch
As shown in FIG. 5, b is a pair of demultiplexers 9 arranged between the downstream output / upstream input terminal 7 and the downstream input / upstream output terminal 8, and is temporarily connected to the upstream path 10 and the downstream path 11. After being demultiplexed, they are mixed again. The upstream amplifier 12 and the downstream amplifier 13 are inserted and arranged in the paths 10 and 11, respectively. Further, in the middle of the upstream path 10, the switching device 14 is connected in series with the upstream amplifier 12.
Is provided, and the switch device 14 is turned on / off at a desired timing by a signal from the control unit 15. That is, for example, when the switch device 14 is in the closed state and there is a signal passing characteristic as shown in FIG. 6A, when the switch device 14 is opened, the level-cut characteristic as shown in FIG. 6B. Becomes Therefore, for example, when communicating between one terminal device 3a and the center 2, the relay amplifying device 5a for high frequency transmission line placed in the transmission system between them is set in the passing state, and the relay amplifying device 5b for other high frequency transmission line is placed. By blocking at least one of the relays, the noise generated in the relay amplifier existing on the terminal device 3b side of the relay amplifying device 5b for the high frequency transmission path is prevented from being transmitted to the center 2 side. This ensures an appropriate signal voltage level difference.

[0005]

However, the above-described conventional relay amplifiers 5a and 5b with a reverse switch are provided.
However, since the switching device 14 is configured to control the passage or blocking of the entire transmission frequency band by the on / off control of the switching device 14, the following problems occur.
That is, between the relay amplifiers 5a and 5b and the center 2, the switch device 14 in the relay amplifiers 5a and 5b is provided.
State communication is performed in order to monitor the open / closed state, the transmission line level in the relay amplifiers 5a and 5b, the voltage of the received power, the state of the internal temperature, etc. Communication such as status monitoring of the relay amplifiers 5a and 5b located on the further downstream side cannot be performed.

The present invention has been made in view of the above background, and an object of the present invention is to provide a high frequency transmission capable of constantly communicating a status signal indicating the status of the relay amplifier between the relay amplifier and the center. It is to provide a relay amplifier for a road.

[0007]

In order to achieve the above-mentioned object, in a relay amplifying device for a high frequency transmission line according to the present invention, it is provided in a bidirectional high frequency electric signal transmission line, branched once, and then joined. A relay amplifier having an upstream path and a downstream path, and an amplifier for amplifying an information signal provided in the path, wherein only an opening / closing switch means and a predetermined frequency band are provided in the middle of the upstream path. The filter means to be passed was inserted in parallel.

[0008]

When the switching means is closed, the upstream transmission system is in a conducting state at all frequencies, and therefore noise signals and other noise signals are transmitted to the upstream center as they are. Further, when the switch means is opened, upstream information transmission is performed through the filter means. That is, it is possible to pass only a predetermined frequency band. Therefore, by setting the frequency of the signal to be transmitted, such as the state signal indicating the control state of the relay amplifier, in the above band, information is always transmitted to the upstream side regardless of whether the switch means is opened or closed. In addition, noise is cut and is not transmitted to the upstream side because the frequency band other than the predetermined frequency band is cut off.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a relay amplifying device for a high frequency transmission line according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of the present invention. As shown in the figure, the basic configuration of appropriately demultiplexing a signal that has entered the device and passing it through a desired path of the branched up path or down path is the same as the conventional one. That is, the first branching filter 22 is connected to the downstream output / uplink input terminal 20, and the upstream branch 24 and the downstream branch 26 are separated via the first branching filter 22. Then, a downlink amplifier 27 is inserted and arranged in the downlink path 26, and a signal amplified by passing through the downlink amplifier 27 is output to the second demultiplexer 2
8 to the downstream input / upstream output terminal 30. On the other hand, the upstream path 24 is connected to the second demultiplexer 30 via the switch device 32 for performing on / off control and the upstream amplifier 33, which are connected in series as in the conventional case. The switch device 32 is turned on / off at a predetermined timing via the control unit 34. That is, in this example, the distributor 35 is provided in the downstream path 26.
And a control signal for performing the on / off control entered from the center side through the coaxial cable into the downlink input / upstream output terminal 30 of the relay amplifier via the distributor 35. To tell.

Further, various sensors are built in the control unit 34, and a state signal indicating the operating state in the relay amplifying device detected by the sensor is issued from the control unit 34, and the up route The mixer 36 provided in the unit 24 joins the upstream path 24 and is transmitted to the center side.

Here, in the present invention, a bandpass filter 37 is connected in parallel with the switch device 32 in the upstream path 24. The band pass filter 37 plays a role of passing only a predetermined frequency band in the transmission frequency band. That is, when there is a transmission signal as shown in FIG. 2A, only a predetermined frequency band is allowed to pass and other frequency bands are blocked as shown in FIG. 2B.

Therefore, when the switch device 32 is closed based on the control signal from the control section 34, the terminals of the bandpass filter 37 are brought into conduction, so that an information signal sent from a normal terminal device to the center and , The upstream signal such as the status signal indicating the control status of the relay amplifier is directly input to the downstream input / upstream output terminal 3 via the switch device 32.
It reaches 0. On the other hand, when the switch device 32 is in the open state, the upstream information transmission is regulated by the characteristics of the bandpass filter 37 and is passed through only the predetermined frequency band and is transmitted to the downstream input / upstream output terminal 30. The electric signal transmitted to the terminal 30 is sent to the center (not shown).

That is, in this example, if the predetermined frequency band of the bandpass filter 37 is adjusted to the frequency of the status signal, the switch device 32 is connected to the downstream side of the relay amplifier in the open state. The status signal from the other relay amplifier is transmitted at the frequency of the predetermined frequency band of the band pass filter 37, so that it can be reliably transmitted to the center regardless of the open / closed state of the switch device 32. Further, if the cutoff frequency is adjusted to the frequency of the noise signal, the noise signal is not reliably cut off and transmitted to the center on the upstream side when the switch device 32 is in the open state, and the electric signal and the noise are surely separated from each other. It is possible to secure the level difference.

FIG. 3 shows a second embodiment of the present invention.
As shown in the figure, in this example, in addition to the downlink output / uplink input terminal 20 and the downlink input / uplink output terminal 30 in the first embodiment described above, a plurality of downlink branch output / uplink branch input terminals 40 are provided. There is. The downstream branch output / upstream branch input terminal 40 has an upstream branch path 42 and a downstream branch path 4 branched from the upstream path 24 and the downstream path 26, respectively.
4 is connected via the third branching filter 46,
A switch device 48 and a bandpass filter 50 are inserted and arranged in the upstream branch path 42. In the figure, reference numeral 52 is a mixing section, and reference numeral 54 is a downstream amplifier. With such a configuration, signal control can be individually performed.

Since the other constructions, functions and effects are the same as those of the first embodiment described above, the description thereof will be omitted by giving the same reference numerals in the drawings.

[0017]

As described above, in the relay amplifying device for a high frequency transmission line according to the present invention, the switching means and the filter means are provided in parallel in the upstream path, so that even if the switching means is opened, a predetermined The signal in the frequency band can pass through the filter means. Therefore, if the carrier frequency of the status signal indicating the control status of the relay amplifier is set to the predetermined frequency, the status signal can always be transmitted to the center side regardless of the on / off status of the switch means. ..

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a preferred first embodiment of a high-frequency transmission line relay amplifier device according to the present invention.

FIG. 2 is a graph showing operating characteristics of filter means (bandpass filter).

FIG. 3 is a block circuit diagram showing a second preferred embodiment of a relay amplifying device for a high-frequency transmission line according to the present invention.

FIG. 4 is a diagram showing an overall configuration of a bidirectional high-frequency electrical signal transmission line.

FIG. 5 is a block circuit diagram showing an example of a conventional relay amplifier for a high-frequency transmission line.

FIG. 6 is a graph showing operating characteristics of a conventional relay amplifying device for a high frequency transmission line.

[Explanation of symbols]

20 ... Downstream output / upstream input terminal, 22 ... First demultiplexer, 2
4 ... upstream path, 26 ... downstream path, 27 ... downstream amplifier, 2
8 ... Second demultiplexer, 30 ... Down input / up output terminal, 32
... switch device, 33 ... upstream amplifier, 34 ... control unit, 3
5 ... Distributor, 37 ... Bandpass filter (filter means)

Claims (1)

[Claims] 1. A bidirectional high-frequency electric signal transmission path, which has an upstream path and a downstream path that are branched and then merged, and an amplifier for amplifying an information signal is provided in the path. A relay amplifier for a high-frequency transmission path, characterized in that a switching amplifier means and a filter means for passing only a predetermined frequency band are inserted in parallel in the middle of the upstream path.